Drafting machine



Feb. 22, E949. c. H. LITTLE ET AL. 2,462,271

` DRAFTING MACHINE Filed sept. 22 1944 4 sheets-sheet 1 m f l4 P7; \V lQ. `\/f"| i r l 'I lr I l l* ll i |I i;

INVENToR mais Haw/ey nv-e j@ Pkw/@Wam Fell 22, 9j49- c. H. LITTLE ET AL2,4629271 DRAF'TING MACHINE Filed sept. 22, 1944 4 sheets-sheet? Trae/YEyg Feb. 22, 1949. C, H. .TTLE ET AL 1462,27@

DRAFTING MACHINE Filed Sept. 22, 1944 4 Sheets-Sheet 3 M /1 Trae/V575Feb; 22, w49, C. H. LITTLE Em 2,462,27l

DRAFTING MACHINE Filed Sepi. 22, 1944 4 Sheets-Sheet 4 I .l INVENTORSCHARLES Ha/e y fue 1 ByC/#mss #aaa/wohn@ 1 Q wf/WWW@ www atented Feb.22, 1949 UNITED STATES ATENT OFFICE DRAFTING MACHINE Charles HenryLittle, Cleveland Heights, and Charles Hubbard Little, Cleveland, Ohio19 Claims. l

The present invention relates to drafting machines and similar devicescomprising a parallel motion mechanism or arm, one end of which issecured to or is adapted to be secured to a table, drafting board orlike device, affording a Working surface over which the free end of thearm provided with some suitable instrument is adapted to be moved andthe instrument carried thereby maintained parallel in successivepositions.

Where the working surface is inclined, the parallel motion arm, whichusually comprises two relatively movable sections, will not remain inany predetermined position without being held therein by the operator.In an attempt to overcome this difficulty, various counterpoisemechanisms have been proposed but none of the counterpoise mechanismsheretofore employed have been entirely satisfactory for various reasons,such as, that they give the machine a bulky and ungainly appearance,impose limitations upon the otherwise normal range of movement of theparallel motion arm, are not effective for all board angles, etc.

One of the principal objects of the present invention is the provisionof a novel and improved drafting machine or similar device, including aparallel motion arm and counterpoise mechanism therefor, which machineis so constructed and arranged that it will be accurate in operation andwill not have the appearance of being bulky and ungainly, and in whichthe counterpoise mechanism will not interfere with the otherwise normalrange of movement of the parallel motion arm and will counterbalance orcounterpoise the same in all positions.

Another object of the invention is the provision of a novel and improveddrafting machine or like device comprising a parallel motion arm andcounterpoise mechanism therefor effective to balance the parallel motionarm at all board angles from zero to ninety degrees.

Another object of the invention is the provision of a novel and improveddrafting machine or like device comprising a parallel motion arm andcounterpoise mechanism therefor, which counterpoise mechanism isautomatically adjustable for dierent board angles.

Another object of the invention is the provision of a novel and improveddrafting machine or like device comprising a parallel motion arm andcounterpoise mechanism including a helical-type contractional spring forcounterbalancing the parallel motion arm.

Another object of the invention is the provision of a novel and improveddrafting machine or Another object of the invention is the provision ofa novel and improved drafting machine or similar device comprising aparallel motion arm and counterpoise mechanism therefor including ahelical-type contractional spring adapted to be located at the side ofthe drafting board opposite the arm, and means independent of the springfor varying the counterpoising effect thereof to balance the arm atdifferent board angles.

Another object of the invention is the provision of a novel and improveddrafting machine or similar device comprising a wheel and band typeparallel motion arm and counterpoise mechanism for the parallel motionarm including a counterpoise force producing mechanism locatedunderneath or behind the working surface or drafting board and connectedto the arm by means permitting the arm to be adjusted angularly relativeto the counterpoise force producing mechanism.

Another object of the invention is the provision of a novel and improveddrafting machine or similar device comprising counterpoise mechanism forthe parallel motion arm, which counterpoise mechanism includes acounterbalancing device, such as a spring or weight located underneathor behind the drafting board or other working surface and connected tothe arm by means comprising an eccentric o1' substantially eccentric camand a lever interposed between the counterbalancing force producingdevice and the cam for changing the amount of counterpoising forceapplied to the arm so as to provide for different board angles.

Another object of the invention is the provision of a novel and improveddrafting machine or similar device comprising a multi-section parallelmotion arm of the wheel and band type and including means located at theside of the drawing board opposite the arm for counterbalancing thelower or instrument section of the arm independently of the bands of theparallel motion mechanism.

The invention resides in certain constructions and combinations andarrangements of parts and further objects and advantages will beapparent to those skilled in the art to which it relates from thefollowing description of the preferred embodiment with reference to theaccompanying drawings forming a part of this specification in whichsimilar reference characters designate corresponding parts, and in whichFig. 1 is a View of a drafting machine embodying the present inventionattached to a Hamilton Auto-shift drafting table;

Fig. 2 is a fragmentary sectional view of the device shown in Fig. 1,approximately on the line 2-2 of Fig. 1, with both sections of theparallel motion arm positioned at right angles to the upper edge of thedrawing board;

Fig. 3 isa fragmentary sectional view, with portions in .,eievation,approximately on the line 3-3 of Figs. 1 and 5, with the drafting boardin a vertical position and the parallel motion arm in the position shownin Fig. 2;

Fig. 4 is a fragmentary sectional view approximately on the line 4 5 ofFig. 3; and

Fig. 5 is a fragmentary rear view of the device shown in Fig. 1, withthe various parts in the positions shown in Fig. 3.

The drafting machine shown comprises a jointed two-section parallelmotion mechanism orA arm of the wheel and bandtype having an instrumentor ,protractor head A at the free end and .theother end xedly secured,as by wood screws l0, to the drafting board B of a Hamilton "Autoshiitdrawing table, designated generally bythe referencechara-cter C. Theinstrument head A is adapted to be moved about the Working surface ofthe drawing board B and the rulers or other instruments forming a partthereof maintained parallel by the parallel motion mechanism insuccessive positions to which they are moved.

As previously stated, one of the objects of the present invention is theprovision of a drafting machine comprising counterpoise mechanismeffective to balance the parallel motion arm at all board angles withoutattention on the part of the operator as the drawing board is moved fromone angle to another; therefore, the drawings show the drafting machineapplied to an adjustable drawing board. The Hamilton Auto-shift drawingtable referred to is of commercial construction and the drawing board Bthereof can be realily located in either a` horizontal or a verticalposition or in any intermediate position. vA complete description of thetable is not necessary to a full understanding of the present invention.Suffice it to say that the drafting board B is pivotally connected, asby bolts Il, to vertical upriglits i2 located adjacent to opposite endsof the table and vertically adjustable relative to the table proper bymechanism not shown but wellknown in the art.

`The parallel motion mechanism or arm shown, which is the preferredconstruction, comprises two angularly movable sections, each compri-singa pair of wheels of equal diameter encircled by a ilegible band and heldin spaced relation with the band under tension by a strut so constructedas to enclose the band and wheels. The upper or anchor section of theparallel motion mechanism or arm comprises the wheels I3 and I4encircled by an endless band l5 and held in spaced relation by a strut Dcomprising yokes or yoke members i5 and i7 connected by tubular sidemenibers 20 and 2l. The upper yoke l5 is pivotally connected to theanchor assembly E, of which the upper wheel 3 is a part and through themedium of which the parallel motion arm is connected to the drawingboard -B by being fixedly secured to the upper or left-hand end oi anelongated bolt or spindle 22 rotatably supported in the anchor bracketby anti-friction bearings 23 and 2G, 25, '25 adiacent to the upper,intermediate and lower parts thereof, respectively. The

tubelike nut members rotatable in one direction to expand the strut andtense the band and in the opposite direction to release the same so thatthey can befmoved along the side members to lexposes. portionor portionsof the band.

The protractor section of the parallel motion arm is of similarconstruction and comprises equal diameter wheels 30 and 3l encircled byan endless band 32 and held in spaced relation by a strut comprisinglyoke members 33, 34 connected by `tubular side members 35, 36 includingItulziular nut members similar to the tubular `rmt.rnezn bcrspreviouslyreferred to. The wheels [Land at the elbow of thearm are preferably`formed integral and are operatively. connectedto therespectivc struts byanti-friction bearings respectively. The wheel .3| located-attire freeend of the parallelmotion arm forms apart of the instrument head A. Theconstruction. ofthe protractor strut is such that it enclosesthe wheelsand band of the protractorsection.

The instrument A is similarin constructionto that disclosed and claimedin our copending application Serial No. 555,268, filed SeptembergZ,

1944, entitled Drafting machine, and is-not here in shown and describedin detail. :Reference is made tothe aforesaid application foiwacompletedisclosure thereof. Suflice it to saythat the-instrument head Acomprises a rulerlassembly F including a normally rotatable member .45forming one'element of the.protractorpropersandv one or more rulers 4|detachably secured to.a.ruler or chuck arm-42. In addition to theaforementioned elements, the instrument head comprises a normallystationary protractor .element 43, which cooperates with the rotatableprotraetor element previously referred to, to indicatethe angular:position of the ruler or rulers, 4index mechanism including the thumbpiece Mge protractor clamp 55,. and a ruler assembly: clamp d6.

The counterpoise mechanism-showncomprises two helical-type contractionalsprings A5l), .-.Sl locatedbehind or underneaththe drawing" board B forcounterbalancing the anchor.1 and-:protractor sections ofthe'parallelmotion arm, respectively. VThe,.contractional springs50,'.5l1are.p1'eloaded at the Vtime of assembly andi-are'- housed withina. double-'walled tubular member 52, the lower endof-.which is closed by-a member 53 securely fixed to both tubes.V The=doublewa1led tubularmember-52 extends generally'infadirecn tion at right' angles Vto theupper edge of vthe drawing board and is pivotally connected 'to,`,abracket 54 through the medium lof a memberjSS fixed to'the member'52Vand pivotally connected tothe bracket Slby a pin 56. Asy shown, thebracketA 54 is connected to the anchor. bracket -E by machine screwsf'land to the undersideof the drawing board by wood screws58. )Theconstructionris such that the tubular member .452 is'supportedunderneath the drawing board B for rotation Vabout thepin 56 as an.axis, which axis is fixed withrespecttothe anchor bracket.

The purpose of the aforesaid pivotal construction will be hereinafterreferred to.

The counterpoise springs 58, 5l are located between the inner and outerwalls of the member 52 and are concentrically arranged with respect toeach other with their upper ends abutting against the lower ends of twoconcentric members 60, 6l, respectively. The upper ends of the members60, 6l are provided with rollers 62, 63 continuously in contact with thelower or front sides of levers 64, 65, respectively. The lower or frontends of the members 60, 6I are provided with downwardly extendingtubular members 66, 61, respectively, xedly secured thereto. The tubularmembers 66, 61 extend between the counterpoise springs 58, 5I and inaddition to forming guides for the members 60, 6l separate the springs,thus preventing one from interfering with the other. The upper ends ofthe tubes of the member 52 are flared towards each other in such amanner that the counterpoise springs will be retained therein eventhough the inembers 60, 6I and their respective tubes 66, 61 arewithdrawn. This construction facilitates assembly as the counterpoisesprings can be assembled with the member 52 prior to the assembly of themembers 60, 6I therewith.

The levers 64, 65, previously referred to, are interposed between therollers B2, 63, respectively, and ball bearing eccentric cams,designated generally by the reference characters 10, 1|, which cams aresimilar to the ball bearing eccentric cams shown and described in ourcopending application Serial No. 555,267, filed September 22, 1944 and,as shown, comprise commercial ball bearings fixed to eccentrics 12, 13.The levers 64, 65 are pivotally connected to the anchor bracket E by apin 14 fixed in said bracket to one side of the center of the spindle orbolt 22 and so located with respect to the eccentric cams that thelevers extend generally parallel with the upper edge of the drawingboard.

The lower or right-hand cam 1l! which forms a part of the counterpoisemechanism for the anchor section of the parallel motion arm is keyed orotherwise non-rotatably fixed to the 1bolt 22 adjacent to its lower orright-hand end with its center oiset from the center of the bolt 22along the center line of the anchor section of the arm and in thedirection in which the f arm extends. The ball bearing eccentric cam 1|which forms a part of the counterpoise mechanism for the protractor orinstrument section of the parallel motion arm is rotatably supported onthe bolt 22 by an anti-friction bearing 15 with its center oiset withrespect to the center or axis of the bolt 22 in a direction generallyparallel with the length of the instrument section or strut of the armand to the side thereof corresponding to the direction in which thesection extends from the elbow of the arm.

The eccentric cam 1I is operatively connected to the strut of theinstrument section of the arm by a gear 16 xed to a flange 11 formedintegral with the eccentric 13 of the ball bearing eccentric cam 1|. Thegear and flange are concentric with the bolt 22 and the gear iscontinuously in mesh with a pinion 18 fixed to the lower end of a shaft80 rotatably supported in the bracket E by anti-friction bearings 8|,82. The upper or left-hand end of the shaft 80 is provided with a pinion83 continuously in mesh with an internal gear 84 xed to the lower orright-hand side of a pulley 85 rotatably supported on the upper member21 of the bracket E by an anti-friction 6 bearing 86. The pulley isoperatively co'ii-f nected to an equal diameter pulley 81 formedintegral with or attached to the upper side of the yoke member 33 of theinstrument strutby a cable 88 encircling both pulleys and provided withturnbuckles 89 for tensioning the same and adjusting the sectionangularly relative to the counterpoise mechanism proper, as will behereinafter more specifically referred to. Preferably, the cable 88 isconnected to the pulleys 85 and 81 by screws 90, thus reducing theamount of tension which would otherwise be necessary to prevent themfrom slipping on the pulleys. Any rotation of the instrument section ofthe parallel motion arm relative to the drafting board or any forcetending to rotate the same is transmitted by the cable 88, pulley 85,etc., to the ball bearing eccentric cam 1I.

The construction is such that when the parallel motion arm is at rightangles to the upper edger of the drawing board, that is, in theposition' shown in Figs. 2, 3 and 4 of the drawings, the centers of theeccentrics 12, 13 are in line with the points of Contact between thelevers 64, 65 and the ball bearing cams 10, 1I, respectively, and thecenter of the bolt 22, with the result that the forces of thecounterpoise springs are applied in line with the center of the bolt 22and the springs have no tendency to rotate the eccentrics "i2, "i3,` Aseither section of the parallel motion arm is moved out of the aforesaidposition, the eccentric associated therewith is rotated with it and itscenter moved to one side or the other of the center of the bolt 22depending upon the direction in which the section is moved, with theresult that the respective spring associated therewith tends to rotatethe eccentric and thus counterbalance or counterpoise the section.

From the foregoing it will be apparent that for proper operation, acertain predetermined angular relationship must be maintained betweenthe struts and the eccentric cams associated therewith. This does notpresent any particular problem in so far as the anchor strut isconcerned because the desired angular relationship therebetween and theeccentric cam which forms a part of the connection between the strut andthe counterpoise force producing mechanism can be readily eiected at thetime of assembly and with the construction shown the relationshipthereafter remains fixed. However, because the connection between theprotractorstrut and the eccentric cam associated therewith includes thecable 88 which must be tightened at assembly and at various timesthereafter, provision must be made for adjusting the angularrelationship between the protractor or lower strut and its eccentriccam. In the present instance this adjustment is effected by theprovision of the two turnbuckles 89, one in each of the two reaches ofthe cable 88. Without further description, it will be apparent that ifonly one turnbuckle was employed, the angular relationship between thestrut and the eccentric cam would be changed every time the cable wastightened. However,

once the desired relationship is obtained by turn.

ing one or the other of the turnbuckles, the cable can be tightenedwithout disturbing the relationship by turning each turnbuckle an equalamount. Alternatively, other means may be provided for adjusting theangular relationship between the strut'and the eccentric cam eitherl atassassin.

the vtime of assembly or subsequent `.,therfeiio, .if desired.

Because different.counterbalancing forces .are required to balance thearm at anyigiven pos tion .on the drawing board for different boardangles, provision is made for changing the counterbalancing Veiect ofthe counterpoise springs as .the board angle is changed. vIn .thepresent instance this uis accomplished withoutadjusting the springsor,in other words,independentlyoi the springs by changing the point ofapplication of the force of the springs .tothe ileversl, '6i interposed'between the rollers 52, and -the ballbearing eccentriccams fifi, `lll.As shown, the point o application ofthe counterpoise spring pressuresagainstthe levers EsLfSf-is-varied in accordancewith the board `angle bymoving the member 512 about the pin 56, previously referred to, as apivot, thus moving the rollers 62, 68 along the levers Gil, e5. Theconstruction is such that the rollers 62, 63 caribe located at any densired position along the levers Bil, inter-mediate a line through thepivot 'lll or through-the bolt.

Preferably the member 52 is moved automatically with a change in theboard angle. .As shown, this is accomplished by a roller 32 connected tothe upper or front side of a lever $3 intermediate the ends of thelever, which roller engages within a cam slot S4 in the member 5. Oneend of the lever 93 is pivotally connected by a'pin S5 to a'projectionon the bracket and the other end thereof is pivotally connected by a pin95 to the upper or rear end of a rod 91, the lower or front end of whichrod is pivotally connected'by'apin '33 to a bracket Se 'fixed to achannel member i953 bolted to the upright-s S2 and which channel memberis a part of the Autoshift table, previously referred to. The length ofI-tl'ie rod `97 can be adjusted by a turnbnckle lOl. In view of the factthat the force-requirer to balance the parallel motion arm does not varydirectly with the board angle, the slot S!! assumes the curved 4shapeshown in the dra-Wings when itis desired that the counterpoise mechanismbalance the arm at all board angles between zero and ninety degrees.rEhe shape can be computed by measuring the force required tocoi-.interbelance the arm at different board angles or by thecut-and-try method. The relative positions of the member 52, etc., whenthe board is in a vertical position, is that shown in full lines in Fig.5. The relative positions of the various parts with the board in ahorizontal position is shown in dot-dash lines and it YWill Ybeunderstood that Vfor intermediate board angles the parts will assumeintermediate positions.

The following table gives approximately the counter-balancing forcerequired for different board-angles in percent of that required With theWhile the preferredmeans for Varying the counterpoising, force at anaccelerated rate relative to the rate `at which the angle of thel boardis-Ivaried has been described with considerable 8 detail, it. is to :be:understood `that the :present invention contemplatesthe use .of meansAother than thecurved slotlconstruction shown.

.es previouslyfstated, ,the/counterpoise springs arepreloadednt `thetime 'of assemblyand the -truction employed permits the use of relayheavy, substantially constant pressure springs,lthussredueing thedimensional requirements oflthe deviceand making amore compactzonstruction. The fact that the counterpoise springs -are housed withinthe member 52 pro- :luces a Very safe construction and one wherein thecounterpoise mechanism 4is at leastpartially operable even thoughone vorboth of the counterpoise springs may break.

Front the foregoingV description of the' preferred embodiments ofthe'invention, it will belapparert that the Vobjects'lieretoforeenumeratedjand others have'been accomplished and that a novel Vandlfnproved drafting machine or like device `has been provided comprisingcounterpoise mecha- 'a vin of improved design andconstructiomwhichcounterpoise mechanism does not 'interfere .with *be otherwise ullmovement of the parallel moarm, doesnot give the device a bulky and -niyappearance', isout of the Way ofthe op ator, and is effective throughoutthe ran'ge i .iovernent por the parallel` motion Varmand for all`diierent board angles.

While .the preferredembodiments of the invenfion'have been ,describedwith considerable the invention islnot limited to therparticuconstruction shown and. it is our intention Yto "by cover alladaptations, niodications and es thereof which come WithintlieVpracticeof those skilled in the art to which .the invention relates and,within the spirit and scope of the appended claims.

`Having thus described our invention, ,what we .-iaimds:

V1. ln a counterpoise mechanism fora draft-4 ing machine or likedeviceincluding aparallel motion mechanism orarm adapted tobe connectedto a drawingboardor 'thelike formovel:nent overv at least'a portion ofOneside. thereof, a contractional helical springlocated-atthe side ofsaid drawing board .opposite ,said arm for counterpoising said arm, Yandmeans .automaticallyY )perabie upon variation. of the board .angle orvarying the i counterpoising eiect of said spring.

2. In `a counterpoise mechanism. fora drafting nine or likedeviceincluding a parallelmoriechanismcr ,arm-adapted.Y to be connected toadrawing board or the like for movement over. atleast-a portionor'.oneiside thereof, a contractional helical spring located Vat ther-sideof saiddrawing Vboard opposite'said arm forcounerpoising said ,arm. andmeans automatically operable .upon variation of the boardangle forvaryingthe -counterpoising eifectof said spring anaccelerated rateassaid board angle increases.

,3..In a counter-poise mechanism for a drafting machine Lor .like deviceincluding a multi-section, parallclmotion mechanisnror arm adapted tobeconnected to adrawing board or-the like for movement ovenat least'a`portion thereof, a contractionallhelical-spring located at the side ofsaid drawing' board opposite said arm for `counterbalancing asection ofsaid arm, an eccentric cam,: means'a'dapted to operatively connect saideccentricV cam tothe section of said ,arm tolbe balanced-bysaid-spring,-a :lever interposedbetween said spring and said eccentriccam. means for pivotally supporting said lever at one side of saideccentric cam, and means for changing the point of application of theforce of said spring to said lever.

4. In a counterpoise mechanism for a drafting machine or like deviceincluding a multi-section, parallel motion mechanism or arm adapted tobe connected to a drawing board or the like for movement over at least aportion thereof, a contractional helical spring located at the side ofsaid drawing board opposite said arm for counterpoising said arm, aneccentric cam, means for operatively connecting said eccentric cam to asection of said arm, a lever interposed between said spring and saideccentric cam, means for pivotally supporting said lever at one side ofsaid cam, a member enclosing said spring, means for pivotally supportingsaid member, and means for rotating said member about said pivot forchanging the point of application of the force of said spring to saidlever.

5. In a counterpoise mechanism for a drafting machine or like deviceincluding a multi-section, parallel motion mechanism or arm adapted tobe connected to a drawing board or the like for movement over at least aportion thereof, a contractional helical spring adapted to be located atthe side of said drawing board opposite said arm for counterpoising asection of said arm, an eccentric cam, means for operatively connectingsaid eccentric cam to a section of said arm, a lever pivotally supportedat one side of said eccentric cam and having a part thereof interposedbetween said spring and said cam, a member for enclosing said spring,means for pivotally supporting said member, and means actuated by achange in board angle for rotating said member to change the point ofapplication of the force of said spring to said lever.

6. In a counterpoise mechanism for a drafting machine or like deviceincluding a multi-section, parallel motion mechanism or arm adapted tobe connected to a drawing board or the like for movement over at least aportion of one side thereof, means comprising counterpoise forceproducing mechanism adapted to be located at the side of said drawingboard opposite said paralle] motion arm, and means including twointernal gears located at opposite sides of the drawing board andconnected by a shaft provided with pinions for operatively connectingsaid counterpoise force producing means with a section of said parallelmotion arm to be counterbalanced thereby.

7. In a counterpoise mechanism for a drafting machine or like device,including a multi-section, Wheel and band type, parallel motionmechanism or arm adapted to be connected to a drawing board or the likefor movement over at least a portion of one side thereof, meanscomprising counterpoise force producing mechanism adapted to be locatedat the side of said drawing board opposite said parallel motion arm,means including two relatively rotatable members for operativelyconnecting said counterpoise force producing mechanism to a section ofsaid parallel motion arm to be counterbalanced thereby, and means foradjusting said members angularly relative to each other.

8. In a counterpoise mechanism for a drafting machine or like device,including a multi-section, parallel motion mechanism or arm .adapted tobe connected to a drawing board or the like for movement over. at leasta portion of one side thereof, a contractional helical spring adapted tobe located at the side of the drawing board opposite said arm forcounterpoising a section thereof, means including two relativelyrotatable members for operatively connecting said spring to the sectionof said parallel motion arm to be counterbalanced thereby, andnieans'for adjusting said members angularly relative to each other.

9. In a drafting machine or like device adapted to be used on aninclined drawing board or the like, an anchor member adapted to beconnected to a drawing board or the like, a wheel fixed with respect tosaid anchor member andA adapted to be located at one side of the drawingboard to which the anchor member is attached, a strut rotatablysupported concentric with said wheel, a second wheel spaced from saidfirst wheel, means for pivotally connecting said second wheel to saidstrut, a flexible band encircling said wheels, a third wheel concentricwith said second wheel and fixed with respect thereto, a'second strut,means for pivotally connecting said second strut to said third wheel forrotation about an axis concentric therewith, a fourth wheel spaced fromsaid third wheel, means for pivotally con-v necting said fourth wheel tosaid second strut, a flexible band encircling said third and fourthwheels, a member located adjacent. to said rst wheel, means forsupporting said member for rotation about an axis concentric with theaxis of said first strut, means for operatively connect' ing said memberwith said second strut, force producing means for counterpoising saidsecond strut and adapted to be located at the side of the drawing boardopposite said wheels, and means for operatively connecting said forceproducing means to said member. v

10. In a drafting machine or like device adapted to be used on aninclined drawing board or the like, an anchor inember'- adapted to beconnected to a drawing board or the like, a wheel fixed with respect tosaid anchor member and adapted to be located at one side ofthe drawingboard'to which the anchor member is attached, a strut rotatablysupported concentric with said wheel, a second wheel spaced from saidIfirst wheel, means for pivotally connecting said second wheel tov saidstrut, a flexible band encircling said wheels, a third wheel concentricwith said second wheel and fixed with respect thereto, a second strut,means for pivotally connecting said second strut to said third wheel forrotation about an axis concentric therewith, a fourth wheel spaced fromsaid third wheel, means for pivotally connecting said fourth wheel tosaid second strut, a flexible band encircling said third and fourthwheels, a member located adjacent to said first wheel, means forsupporting said member for rotation about an axis concentric with theaxis of said first strut, means for operatively connecting said memberwith said second strut, a spring for counterpoising said second strutand adapted to be located at the side of the drawing board opposite saidwheels, and means for operatively connecting sa'id spring to saidmember.

11. In a drafting machine or like device adapted to be used on aninclined drawing board or the like, an anchor member adapted to beconnected to a drawing board or the like, a wheel fixed with respect tosaid anchor member and adapted to be located at one` side of the drawingboard lto which the anchormember, is attached; a strut rotatablysupported concentric with vsaid wheel,

aprecian second wheel spaced fromk said first wheel, means forpivotallyfconnecting said secondi wheel to said strut; a flexible" bandencircling said wheels', a third wheel concentric with said second wheeland fixed' with respect thereto, a second strut', means forpivotallyconnecting said second strutto said thirdY wheel for rotationaboot an axis concentric therewith, a fourth wheelspaced from said thirdwheel, means for pivotally connectln'g' said fourthwheel tosaid secondstrutA a liexible band encircling' saidY third and fourth wheels', amemberlo'cated adjacent to said first wheel, means for supporting saidmember' for rotationabout anaxis concentric with the axis ol said'iirststrut, means for operatively connect-- ing saidA member with saidvsecond strut, producing'me'ans for counterpoising said second strut andadapted toV be located at the side of the drawing board opposite saidwheels, means for operatively connecting said counterpoise forceproducing meansto said member, and means for aut'omaticallychan'ging thecounteipoising effect of said force producing, means upon a change or"board angle.

12; In a drafting machine or like device u adapted to be used on' aninclined drawing board or the like; an anchor'member adapted to beconnected to a drawing board or`th'e like, a" wheel fixed with respect'yto said anchor member and adapted to beloc'atedat'oneside of the drawingboard' to whichtheanchor member is attached, a strut' rotatably"supported concentric' withA said wheel, a second wheel spaced from saidfirst wheel, means for pivotally connecting saidl second wheeltosaidstrut, a flexible band encircling said' wheels, a third wheel concentricwith said second4 wheel and fixed with respect thereto, a second strut,means for pivotall'y connecting'said second strut to saidthirdwheelforrotation about an' axis concentric therewith, a fourth wheel spaced'from' said third wheel, means for pivotall'y connecting said'fourthwheel'to' said second strut, a flexible band* encircling said thirdL andfourth Wheels, a member located adjacent tofv sai'd first wheel, means'for' supporting said' member for rotation about an axis concentric withVthe axis of said'flrst strut', means for operatively' connecting saidmember with said second strut, .a spring for counterpoisi'ng saidysecond; strut' andA adapted to be located at the side ci the' drawingboardr op'- p'osite said'A wheels, means for operatively connecting'saidspring to said' member, and means for' automatically changing theYcounterpoising eiect of said spring upon a change-of boardlangl'e.

13. In adraf-ting machine or like device adapted' to be used on aninclined drawing board or the like, an anchor member adapted to beVcon'- nected to a drawing board or the like, a wheel lxed withx respectto' said anchor member and adapted tobe located at one' sid'e of thedrawing board to whichB the anchor member is attached, a strutrotatably: supported concentric with said wheel, a'- secondwheel' spacedfrom said first wheel, means forI pivotally connecting' said secondWheel toisai'd strut, aflexible band' encircling said wheels, a. third.Wheel. concentric with. said second wheel and xedz with respect thereto,a second` st11utmeans for. pivcta-lly connecting said second-strut to.said third wheel for. rotation about anv axis concentric therewith, afourth wheel spaced. from: said third4 wheeh means for piyotallyconnecting. said` fourth wheel to, said; second strut, a flexible band.Vencircling, said third and. fourth wheels,.a fth Wheellocated ad'iacentto saldii'rst wheel. means for supportingv said' fth wheel for rotationabout an axis concentric with the axis of. said rst strut, a sixth wheelconcentric with saidE second and third wheels an-d iixed to said secondstrut, a flexible band encircling said lth and sixth wheels,counterpoise force producing means'. for counterpoising said secondstrut and adapted to be located at the side of the `drawing boardopposite said wheels, and means for operatively connecting saidcountcrpoise force producing means to said' fth wheel.

14.- In a drafting machine or like device adaptedfto be'used'on aninclined drawing board or the like, an anchor member adapted to beconnected to a drawing board or the like, a wheel fixed with respect tosaid anchor member and adapted to be'located at one side of the drawingboard to which the anchor member is attached,

astrut'rotatably supported concentric with said wheel, asecond' wheelspaced from said first wheeli meansfor pivotally connecting saidsccond'wheel'to saidv strut, a flexible band encircling said wheels, athird wheel concentric with said second wheel and nxed with respectthereto, a, second" strut, means for pivotally connecting saidsecondistrut to' saidthird-wheel for rotation about anv axis concentrictherewith, a fourth wheel spaced from said third wheel, means forpivotally connectingsaid fourth wheel to said second strut, anexibiebandencircling said third and fourth Wheels, ,a ith wheel located adjacentto said rst wheel, means for supporting said fth wheel for rotationlabout. an'.y axis concentric with the axis of. saiozfirst-Y strut, asixth. wheel concentric with said. second and.' third wheels and fixedto said second'st1ut,a-flexible-band encircling said Iifthandsixthwhcels,- a spring foricounterpoising said second strut adaptedtorbe located at thev side of thedrawing' board' opposite said wheels,means ier operatively connecting said spring tosaid iifth wheel, andmeans for automatically changing the counterpoising eect of said springupon a change of boardiangle.

l5, In a vdrafting machine.' or like device adapted to. be used onaninclined drawing board or the like, an anchor member adapted to beconnected to' ay drawing board or'the like, a wheel fixed with respectto said anchor member and adapted to be located at one side of thedrawing board towhichA the. anchor member is attached, a spindlerotatably supported in said anchor member concentric with said wheel andadapted to extend to opposite sides of the drawing board, a strut xedwith respect tosaid spindle, a second wheel spaced. from said iirstWheel, means for pivctally connecting said second wheel to said strut, aexible band encircling said wheels, a spring adapted to be located atthe side of said drawing board opposite said wheels, means foroperatively connecting said spring to said spindle, a third wheelconcentric with said second wheel and fixed with respect thereto, asecond strut, means for. pivotally connecting said second strut to saidthird'wheel forrotation about an axis concentric therewith, a fourthwheel spaced from said third wheel"l means for` pivotally connecting,rsaid fourth wheel to said second strut, a exible band encircling saidthird and fourth wheels. a iifth wheel located adjacent to said firstwheel, means for supporting said ith wheel for rotation about an axisconcentric with the axis of said spindle, a sixth wheel concentric withsaid second and third Wheels and fixed to saidv second strut, a exiblehand encircling said fth and sixth wheels, a second spring' locatedadjacent to said first spring,

i3 and means for operatively connecting said second spring to said fifthwheel.

16. In a drafting machine or like device adapted to be used on aninclined drawing board or the like, an anchor member adapted to beconnected to a drawing board or the like, a wheel fixed with respect tosaid anchor member and adapted to be located at one side of the drawingboard to which the anchor member is attached, a spindle rotatablysupported in said anchor member concentric with said wheel and adaptedto extend to opposite sides of the drawing board, a strut fixed withrespect to said spindle, a second wheel spaced from said first wheel,means for pivotally connecting said second wheel to said strut, aflexible bandencircling said wheels, a spring adapted to be located atthe side of said drawing board opposite said wheels, means foroperatively connecting said spring to said spindle,

. a third wheel concentric with said second wheel and xed with respectthereto, a second strut, means f-or pivotally connecting said secondstrut to said third wheel for rotation about an axis concentrictherewith, a fourth Wheel spaced from said third wheel, means forpivotally connecting said fourth Wheel to said second strut, a flexibleband encircling said third and fourth wheels, a fthrwheel locatedadjacent to said rst wheel, means for supporting said fifth wheel forrotation about an axis concentric with the axis of said spindle, a sixthwheel concentric with said second and third Wheels and fixed to saidsecond strut, a flexible band encircling said fifth and sixth wheels, asecond spring located adjacent to said first spring, means foroperatively connecting said second spring to said fifth wheel, and meansfor automatically changing the counterpoising effect of said springsupon a change o board angle.

17. In a drafting machine or like device adapted to be used on aninclined drawing board or the like, an anchor member adapted to beconnected to a drawing board or the like, a wheel xed with respect tosaid anchor member and adapted to be located at one side of the drawingboard to which the anchor member is attached, a spindle rotatablysupported in said anchor member concentric with said wheel and adaptedto extend to opposite sides of the drawing board, a strut xed withrespect to said spindle, a second wheel spaced from said first wheel,means for pivotally connecting said second wheel to said strut, aflexible band encircling said wheels, a

cam operatively connected to said spindle and J, adapted to be locatedat the side of the drawing board opposite said wheels, a spring adaptedto be located at the side of said drawing board opposite said wheels,means for operatively connecting said spring to said cam, a third wheelconcentric with said second wheel and fixed with respect thereto, asecond strut, means for pivotally connecting said second strut to saidthird wheel for rotation about an axis concentric therewith, a fourthwheel spaced from said said third wheel, means for pivotally connectingsaid fourth wheel to said second strut, a flexible band encircling saidthird and fourth wheels, an instrument operatively connected to saidfourth wheel, a fifth wheel located adjacent to said first wheel, meansfor supporting said fifth wheel for rotation about an axis concentricwith the axis of said spindle, a sixth wheel concentric with said secondand third wheels and fixed to said second strut, a exible bandencircling said fifth iii) and sixth wheels, a second cam locatedadjacent to said first cam, means for supporting said second cam forrotation about an axis concentric with the axis of said spindle, meansfor operatively connecting said fifth wheel and said second wherebythey'T rotate in predetermined relation upon rotation of either, asecond spring 1ocated adjacent to said first spring, means foroperatively connecting said second spring to said second cam, and meansadapted to be operatively connected to the drawing board forautomatically changing the counterpoising effect of said springs uponvariation of the board angle.

18. In a drafting machine or like device 4adapted to be used on aninclined drawing boardor the like, an anchor member adapted to beconnected to a drawing board or the like, a wheel fixed with respect tosaid anchor member and adapted to be located at one side of the drawingboard to which the anchor member is attached, a spindle rotatablysupported in said anchor member concentric with said wheel and adaptedto extend to opposite sides of the drawing board,v

I respect thereto, a second strut, means for pivotally connecting saidsecond strut to said third wheel for rotation about an axis concentrictherewith, a fourth wheel spaced from said third wheel, means forpivotally connecting said fourth wheel to said second strut, a flexibleband encircling said third and fourth wheels, an instrument operativelyconnected to said fourth wheel, a fifth wheel located adjacent to saidfirst wheel, means for supporting said fth wheel for rotation about anaxis concentric with the axis of said spindle, a sixth wheel concentricwith said second and third wheels and fixed to said second strut, aflexible band encircling said fifth and sixth wheels, a second camlocated adjacent to said first cam, means for supporting said second camfor rotation about an axis concentric with the axis of said spindle,means for operatively connecting said fifth wheel and said second camwhereby they rotate in predetermined relation upon rotation of either, asecond spring located adjacent to said first spring, and means foroperatively connecting said second spring to said second cam.

19. In a drafting machine or like device adapted to be used on aninclined drawing board or the like, an anchor 'member adapted to beconnected to a drawing board or the like, a wheel ilxed with respect tosaid anchor member and adapted to be located at one side of the drawingboard to which the anchor member is attached, a spindle rotatablysupported in said anchor member concentric with said wheel and adaptedto extend to opposite sides of the drawing board, a strut fixed withrespect to said spindle, a second wheel spaced from said first Wheel,means for pivotally connecting said second wheel to said strut, aflexible band encircling said wheels, a cam operatively connected tosaid spindle and adapted to be loc-ated at the side of the drawing 12.5boardiaoppositezsaidfwheels, a compression spring ada-ptewtobef-locatediat theside-of said drawingIrv board-oppositesaid wheels,means `for operatively connecting said. spring; to ,said cam Vcomprisinga lever pivotally supported at one side of said cam andoperativelyconnectedthereto; a third wheel concentric with-said second=whee1 andxed with respecttheretof a secondrstrut, meansfor pivotally connectingsaid, second strutto said-third Wheelor rotation about an axisconcentric therewith,A a'fourth wheel. spaced from said thirdwheel,means forVV pivotall'y` connecting said fourth wheel to said secondstrut, a exiblefband encircling said vthird and fourth wheels, aninstrument operativelyconnected` to said fourth wheeLa fth Wheel.located adjacent to saidvirst wheel, means for. supportingsaidfth wheelforl rotation about an axisconcentric with the axis of said spindle,a'.sixth ,wheel concentric with` said second and thirdw-heels. and Xedtosaid second strut, a n

flexible band encircling said ifthA and sixth Wheels,.1neans1foradiusting'said wheels angularl'y with respect to each other; a secondcam located adjacent to said' first cam, means forsupporting1saids'econd cam for rotation about an aXisconc'entric withthe aXis of said spindle, an internalgear ii'xed to said fth Wheel, aseco'nditernal gear Xed to said second cam, a second-spindle rotatablysupported in said anclior member and provided'w'ith pinion gears in,niesli Witl saidinternal'gears, a second compress'ion spri'glocatedadjacent to said rst spring,

" connected to the drawing board for automatically,v

rotating said springs about said axis upon varia tion of the board anglefor increasing thecolun? terpoising effect of said springs at anaccelerated rate as the board angle increases.

CHARLES HENRY LITTLE. CHARLES HUBBARD LITTLE.

REFERENCES CITED The following references are of recordin; the le ofthis patent:

UNITED STATES PATENTS Number Name `Dato 2,164,215 Little ,June 27, 19392,228,140 Little ,Jan; 7, 1941 2,330,970 Harriman Oct. 5; 1943 FOREIGN'PATENTS Number Country Date 175,183V Great Britain Feb. 16, 1922503,102v Great Britain` i Mar. 31, 19,39

